The present invention relates to an arrangement for stamping an outer surface of thermoplastic shaped bars immediately after their formation. More particularly, it relates to an arrangement for stamping an outer surface of a synthetic thermoplastic bar material in thermoplastic condition which has mutual guiding a bar material, and a rotary stamping tool having a working surface which is shaped in correspondence with a desired pattern to be stamped and rolls over the bar material to stamp the desired pattern on the latter.
Arrangements of the above mentioned general type are known in the art. One known arrangement is disclosed in U.S. Pat. No. 2,075,735. It describes a stamping arrangement which is located after a forming arrangement and provided with stamping bodies which rotate on a conveyor band in caterpillar-like manner, are arranged at both sides of a newly produced shaped member to be stamped, and acts upon the latter. For this purpose, the stamping outer surface can also be heated. When a pattern must be stamped on the extruded shaped member, it is formed complementary in the stamping outer surface and pressed into the shaped member. The known arrangement is expensive to manufacture. Moreover, the bar material, especially when it is hollow as is the case in many applications, cannot be supported from inside to withstand the stamping pressure. This can lead to undesirable deformations. The above described stamping of the outer surface is desirable, for example, for visible surfaces of synthetic plastic shaped bars which are used for and form blinds, window and door frames, window shutters, etc. Research has been conducted to provide such extruded hollow shaped bars with a hot-stamped pattern. However, the results are not satisfactory, since unevenness of the outer surface of bars leads to defective stamping. Thin-walled shaped members cannot be hot-stamped in general.